X86/nVMX: handle_vmon: Read 4 bytes from guest memory

Read the data directly from guest memory instead of the map->read->unmap
sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which
assumes that there is a "struct page" for guest memory.

Suggested-by: Jim Mattson <jmattson@google.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b46136b099b8ed0f959137d3aacd883f4c0c0eb8..9b1973cc1e75d2427c5df585906baf976524896c 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4264,7 +4264,7 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 {
        int ret;
        gpa_t vmptr;
-       struct page *page;
+       uint32_t revision;
        struct vcpu_vmx *vmx = to_vmx(vcpu);
        const u64 VMXON_NEEDED_FEATURES = FEATURE_CONTROL_LOCKED
                | FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
@@ -4313,18 +4313,10 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
        if (!PAGE_ALIGNED(vmptr) || (vmptr >> cpuid_maxphyaddr(vcpu)))
                return nested_vmx_failInvalid(vcpu);
 
-       page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
-       if (is_error_page(page))
+       if (kvm_read_guest(vcpu->kvm, vmptr, &revision, sizeof(revision)) ||
+           revision != VMCS12_REVISION)
                return nested_vmx_failInvalid(vcpu);
 
-       if (*(u32 *)kmap(page) != VMCS12_REVISION) {
-               kunmap(page);
-               kvm_release_page_clean(page);
-               return nested_vmx_failInvalid(vcpu);
-       }
-       kunmap(page);
-       kvm_release_page_clean(page);
-
        vmx->nested.vmxon_ptr = vmptr;
        ret = enter_vmx_operation(vcpu);
        if (ret)